from flask import Flask

app=Flask(__name__)

@app.route('/')
def index():
    return 'Hello World 你好'

@app.route('/a')
def hello_world1():
    return "hello world 你好 a"

def hello_world2():
   return 'hello world'

app.add_url_rule('/', 'hello2', hello_world2)

if __name__=="__main__":
    app.run()